They’re sassy like the Spice Girls and color-coded like the, er, Teletubbies. The Marvelous Wonderettes are the most made-to-order girl group there never was, a fact that doesn’t necessarily make this prefab four any less entertaining.

In fact, a lot of the fluffy charm of writer-director Roger Bean’s “The Marvelous Wonderettes” — the cooing love child of a revue and a jukebox musical that’s now playing at the Birch North Park Theatre — comes from its coy sendups of convention.

Each member of the ’50s high-school singing quartet that gives the show its name is a conveniently defined “type.” There’s feisty Betty Jean (very funny Beth Malone), the tomboy in green; slinky Cindy Lou (Lowe Taylor), the glam queen (desperate to be prom queen) in pink; earnest and soulful Missy (Misty Cotton), rockin’ the tangerine; and sweet, squeaky-voiced Suzy (Bets Malone, who also co-directs and choreographs) in demure blue.

The nearly three dozen ’50s and ’60s pop hits showcased in “Wonderettes,” the season-opening production for San Diego Musical Theatre, fit handily with those personalities — and with the voices of the four actors, strong performers all. (And all veterans of the show’s off-Broadway staging.)

The show opens with the Wonderettes serving as entertainment at their own 1958 Springfield High prom, and lamenting boy troubles and BFF squabbles through song. They deliver polished harmonies on “Mr. Sandman” (forget prom dates, these teens need a record deal) as well as some inspired solos — Cotton’s powerhouse take on “Secret Love” and Bets Malone’s gentle rendition of “Hold Me, Thrill Me, Kiss Me” among the standouts.

And beware if you’re seated in the front row: The girls also bring up a “volunteer” to stand in for Missy’s teacher crush Mr. Lee. (The lucky guy at Saturday’s opening-night performance managed to do it with admirable grace and good humor.)

In Act 2, the Wonderettes return for their 10th reunion. And time has marched on (although maybe not at Springfield High — all the championship banners on the gym walls still end at 1958).

Now the girls are in more flamboyant, Supremes-esque get-ups (Bobby Pearce’s costumes, provided by Musical Theatre West, are a major highlight), and performing together again on a set (by Michael Carnahan) that borrows a little from “Laugh-In.”

The songs now reflect the Wonderettes’ love troubles (“That’s When the Tears Start”) dashed dreams (“Maybe”) and renewed hopes (“Rescue Me,” “Respect”). But the fact there’s little sense of a cultural and musical revolution (this is 1968, after all) feels like a lost opportunity, even for a show that doesn’t have all that much on its mind.

The production does get a nice boost from musical director/conductor Don LeMaster and his capable (though only four-piece) band, and the sound quality is rich and full at the historic Birch, San Diego Musical Theatre’s home for this season.

Color this “Wonderettes” a polished bauble of retro fun, even if it’s not the most neuron-stirring show around.